Household sponge



FIG. 1 is a front perspective view of a household sponge showing my new design;

FIG. 2 is a side elevational view thereof, the opposite side being a mirror image;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a reduced bottom plan view thereof. 

The ornamental design for a household sponge, as shown and described. 